froth flush process

Superheaters/Reheaters/MS piping,Condenser

Condensate and Feedwater

HRSG Watersides

FrothFlush™

SigmaClean™

SigmaBlow™

Results:

•Targets

•Steam Chemistry

•Water Cycle Chemistry

•Stabile Operation

Combined Cycle Plant Applications

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Why FrothFlushTM?

• Very high Reynolds numbers and complete turbulence usingsmall quantities of water return the fastest, highest qualityandmost consistent flushing of pipe circuits

• Cleaning to this level prevents contaminates from enteringthe steam generation equipment.

• Improves water chemistry in the HRSG which in turnimproves the ability to achieve steam purity.

• Current cleaning requirements result in minimal feedwaterand condensate suction strainer fouling.

Froth Former Setup

FrothFlush™

6 inch pipe, 1,000 feet in length40 feet per second“Froth” (compressible) Air / Water “slug”

The FrothFlush™ process utilizes short two phase (air/water) frothed slugsdisplaced at velocities of 15 20 meters/sec generating Reynolds numbers of4 5 million to remove both particulate and non particulate contaminationfrom the metal surfaces.

FrothFlush™FullTurbulence

Effectiveness of FrothFlush™ is due to generation of full turbulence thatscrubs particles and salts from pipe & tube surfaces

ImprovedCleanlinessImproved

Cleanliness

• The FrothFlush™ effectiveness in removal of particulate contamination ismonitored by means of Millipore filters. Samples of the flush effluent waterare taken and filters using fine Millipore filters.

• Millipore filters are so fine that the water sample will not flow through the filterwithout the aid of a vacuum to draw the sample water through the filter.

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• The effectiveness of the FrothFlush™ process in removal of salts from themetal surfaces is monitored by measurement of the conductivity of theeffluent flush water.

• VGB Guideline for acceptable solids in flush water is < 5 mg/l.FrothFlush™ will typically achieve cleanliness of < 0.05 mg/l.

• The VGB Guideline for acceptable flush water conductivity is < 1,000 S/cm.The FrothFlush™ process typically achieves flush water effluent < 50 S/cm.

VGB(ISO-3166-1, British Virgin Islands)

TypicalFrothFlush™

Results

TypicalFrothFlush™

Results

First FrothFlush™ 11th Froth FrothFlush™ Final Effluent on20th FrothFlush™

The above sequence of photographs show the typical results of a FrothFlush™ of a piping system

Millipore®0.45 Micron Patch Test

Millipore®0.45 Micron Patch Test

First FrothFlush™ (500ML)600 S/cm

11th FrothFlush™ (500ml)60 S/cm

Final Acceptable at 20th PassFrothFlush™ (500ml)

15 S/cm

BES&T Millipore™ TestApparatus

System cleanliness far exceeds criteria specified in VGBGuideline and all other water flush methods.

FrothFlush™Preheat & Economizer

Coil Flushing

FrothFlush™Preheat & Economizer

Coil Flushing

• Contamination is proportional to system metal surface area.

• Contamination is proportional to amount fabrication to build a HRSG coils.Cutting, grinding, welding and PWHT generates more contamination.

• Piping typically contributes less contamination than HRSG coils to thesteam cycle as piping has less metal surface and less fabrication.

• The FrothFlush™ process effectively flushes contamination from HRSGpreheat and economizer coil sections at high velocity and high turbulence.

• Effective removal of particulate and non-particulate contamination prior togas turbine first fire minimizes fouling of BFW pump and attemperatorstrainers and sensitive control valve trim.

• Removal of imbedded salts from metal surfaces of the pre-boiler piping andcoils reduces the tine required to achieve steam cycle purity.